Lighting is an essential part of every household. Since its invention, incandescent lamps have been illuminating homes around the globe. However, in the recent years, the incandescent lamp has lost some of its luster as energy conservation becomes a priority in our society. While incandescent lamps are able to provide excellent light quality and performance, they suffer from very low power efficiency. The power efficiency of an incandescent lamp can be as low as 10%, with the majority of the energy consumed by the lamp being dissipated as heat rather than visible light. The incandescent lamp's low power conversion efficiency prompted the development of alternative energy-saving lighting solutions such as high power lighting emitting diode (LED) lamps.
Unlike incandescent lamps, LED lamps do not use electric current to heat a filament to produce light. Rather, they use an electronic driver circuitry to produce light. The design of the driver circuit thus becomes crucial in determining the performance of LED lamps. Despite saving a significant amount of energy compared to incandescent lamps, because of the commercial electronic circuitry currently used, LED lighting products cannot truly replace incandescent lamps when it comes to performance. With respect to technical advantages, the incandescent lamp is able to achieve a very high input power factor from the AC main. A high power factor means that the reactive power drawn from the lamp is low and that the power conversion efficiency is high from the utility side to the lamp. To minimize the size and cost of LED lamps, commercial LED lamp driver designs do not include a power factor correction (PFC) function. As a result, the power factor achieved by current LED products is approximately 30% lower than that of the incandescent lamps. The input current drawn from the LED lamps then contains a significant amount of unwanted harmonics. The presence of these harmonics implies that part of the power is wasted in the form of reactive power when power is transferred from the utility to the lamp.
As mentioned earlier, the electronic driver circuit is the key component that determines the lamp's performance. For LED household lighting products, the driver circuit receives energy from the AC mains and uses this energy to drive the LED semiconductors to ultimately produce light. At present, within commercial LED lamps, there exists a mismatch between the lifespan of the circuit and that of the actual LED devices. LED devices typically have a much longer lifespan than their driver circuits because of the presence of electrolytic capacitors in the commercial circuits. This capacitor is used to provide constant DC (Direct Current) output current to power the LED. The electrolytic capacitor is unreliable and its lifetime is at least 3-4 times lower than that of a LED.
Based on the above, there is therefore a need for systems and circuits which avoid the shortcomings of the prior art and which mitigates if not overcomes the issues associated with the prior art.